Description of the condition
Youth violence is a form of interpersonal community violence, defined by the World Health Organization (WHO) as "violence between individuals who are unrelated, and who may or may not know each other, generally taking place outside the home" (Dahlberg 2002, p.6). Such violence has far-reaching consequences with the most unacceptable being that violence is a leading cause of death in young people. There are an estimated 199,000 global youth homicides per year, which equates to 9.2 per 100,000 of the population (Dahlberg 2002). Mercy 2002 also reports that the rate is significantly higher in young men aged 15 to 29 years (19.4 per 100,000) compared with young women (4.4 per 100,000). The onset of serious violence typically begins from 12 years of age and peaks between 16 and 18 years of age (Office of the Surgeon General (US) 2001), with physical aggression peaking at 15 years of age (Brame 2001).
Beyond the extreme outcome of death, violence is associated with non-fatal injuries, illness, disability, and reduced quality of life (Dahlberg 2002). For instance, the WHO reports that for every youth homicide there are 20 to 40 victims of non-fatal assault (Dahlberg 2002). Indeed, it has been estimated that violence-related morbidity and mortality is responsible for 3% of the global burden of disease (Brundtland 2002). Violence not only impacts its victims, but also the health and well-being of their families, friends, and the wider community (Dahlberg 2002). For example, in deprived inner-city areas, the majority of children have been a victim of, or exposed to, some form of community violence, and this can result in anxiety and depression, and can negatively impact their developmental trajectories (Margolin 2000). Furthermore, parents in an inner-city deprived community reported experiencing high levels of anxiety regarding their own personal safety and that of their children (Weir 2006). This can result in decreased physical activity within this population, which is a risk factor for other adverse health complications (e.g. obesity).
Exposure to violence also puts young people at risk of developing chronic conditions and engaging in health-risk behaviours (Felitti 1998). For instance, exposure to violence as a child is associated with adverse health behaviours (including multiple sexual partners, sexually transmitted infections, alcoholism, and smoking cigarettes) and mood-related disorders (Dube 2003). Furthermore, young people exposed to adverse childhood experiences are at increased risk of developing several of the leading causes of death in adults, independent of their involvement in associated health-risk behaviours (e.g. smoking), including ischaemic heart disease, chronic lung disease, liver disease, and cancer (Felitti 1998).
Engaging in violent behaviour is associated with a range of other health-risk behaviours (Dahlberg 2002). In particular, alcohol use is strongly associated with youth violence and is estimated to be responsible for 26% of male homicides globally (WHO 2006). Moreover, alcohol is frequently involved in non-fatal violence. For example, 42% of people presenting to Accident and Emergency departments in Canadian hospitals with a violent injury were found to have a high blood alcohol level (Macdonald 1999), and the British Crime Survey reported that in 40% of violent incidents, the victim considered the perpetrator to be under the influence of alcohol (Budd 2003). Illicit drug use is also strongly linked with violence, with individuals involved in drugs being at higher risk of becoming either a perpetrator or victim of violence (Atkinson 2009). For instance, a study of methamphetamine users in Los Angeles found that 35% had committed violent behaviour while under the influence (Baskin-Sommers 2006), and one study of young European tourists reported that cocaine use increased the risk of fighting by three-fold (Hughes 2008). Due to the strong links between alcohol and drug abuse and violence, some violence prevention programmes target these risk factors as an indirect means to address violence (Sethi 2010).
Violence also represents inequalities in health, with homicide rates varying greatly between regions and countries, and being higher in low- and middle-income countries than in high-income countries. For example, in Western Europe, Germany has a youth homicide rate of 0.8 per 100,000, whereas in Latin America the rates are significantly higher with Colombia having a rate of 84.4 per 100,000 and El Salvador a rate of 50.2 per 100,000 (Dahlberg 2002; see also Fajnzlber 2002; UNODC 2011). Moreover, rates vary significantly within countries, with young people from the areas of most socioeconomic disadvantage being disproportionately affected (Sethi 2010). For instance, Scottish men under 65 years of age living in the most deprived quintiles have a death rate due to assault that is 31.9 times that of men living in the most affluent quintiles (Leyland 2010). This social patterning of violence is evident across the globe with studies in the US (Cubbin 2000), Brazil (Caicedo 2010), and Russia (Chenet 1998) all reporting an increased prevalence of violence and fatal violent injuries in lower socioeconomic populations.
In addition to socioeconomic factors, longitudinal studies have identified other risk factors for involvement in violent behaviour at the neighbourhood, family, and individual level (Farrington 1995; Hawkins 1995). Neighbourhood risk factors include availability of weapons, laws, and social norms favourable to violence; media portrayal of violence; poor social cohesion; and high levels of residential mobility. Family risk factors include family conflict, poor family management, child abuse, and pro-violent parental attitudes and behaviour. Finally, individual factors include friends involved in problem behaviour, early onset of antisocial behaviour, impulsivity, attention problems, low intelligence, and academic failure. These multiple risk factors demonstrate the complex nature of violence. Indeed, the WHO acknowledged this complexity and has applied an ecological model to understanding and addressing violence that accounts for the complex linkages between the individual, their relationships, and the community and society in which they live (Dahlberg 2002).
As discussed, there are a number of neighbourhood risk factors for violent behaviour and as such the WHO argue that a community in which a young person lives can strongly influence their involvement in violence, with those living in high crime neighbourhoods or neighbourhoods with gangs being more likely to be involved in violence (Dahlberg 2002). For instance, one large study conducted in Chicago reported that spatial proximity to homicide is strongly related to increased homicide rates (Morenoff 2001). Therefore, community-based programmes tend to have been implemented in communities where young people are at risk of community violence due to socioeconomic disadvantage (Buka 2001; Bellis 2008; Sethi 2010), high levels of residential mobility (Dahlberg 2002), and poor social cohesion (Sampson 1997; Martikainen 2003).
More specifically, youth violence prevention programmes are frequently implemented in a school setting (Mytton 2002); however, in low- and middle-income countries the majority of youths will, at most, only attend primary school (UN Statistics Division 2011), and in high-income countries youths engaged in violence are more likely to have dropped out of school (Ellickson 1997). Thus, school-based violence prevention programmes will not necessarily be successful in engaging with the youths most at risk whereas community-based programmes (e.g. The Communities that Care System; Hawkins 2008) have demonstrated the ability to reduce violence, and are able to engage with high-risk adolescents who cannot access school-based programmes.
Description of the intervention
Violence is a multifaceted problem with biological, psychological, social, and environmental risk factors. The most effective prevention programmes tend to act on combinations of the different factors (Dahlberg 2002). Moreover, it is increasingly recognised that a primary prevention approach, which aims to prevent violence before it occurs by addressing these factors, is necessary to reduce violence (Prothrow-Stith 2010). The WHO broadly divide strategies for the primary prevention of violence into direct and indirect approaches (Sethi 2010). First, direct approaches aim to prevent violence by altering the environment in which violence occurs, including: enhancing legislation on buying and carrying knives, and the use of safe drinking vessels (Sethi 2010). Second, indirect approaches target the individual risk and protective factors that affect whether a young person will become involved in violence and include: social development programmes, parenting programmes, and pre-school enrichment programmes (Sethi 2010). The majority of indirect interventions are considered downstream interventions, which are defined as interventions "directed towards individuals to address health behaviours, attitudes, and knowledge" (Smedley 2000, p.28). According to the Health Development Agency, the current available evidence supports the use of downstream interventions (Kelly 2005). More specifically to violence, while there is more evidence to support the use of early indirect interventions, such as parenting programmes and pre-school enrichment (Sethi 2010), these by their nature will not be applicable to adolescents without children of their own. Therefore, the majority of indirect youth violence prevention programmes that target adolescents are social development programmes and focus on increasing the level of protective factors that reduce the risk of involvement in violence (Mercy 2002). Moreover, as it is often not easy or indeed possible to change upstream risk factors for violence (i.e. living in poverty), enhancing a young person's capacity to manage such risk factors and develop resilience is an important area for violence prevention (Dahlberg 2001).
As the evidence suggests that indirect approaches may be more appropriate for reducing violence (Kelly 2005), and because this review is examining the effectiveness of programmes that are targeted at young people aged 12 to18 years, the review will focus on social development programmes that aim to reduce homicide, non-fatal assault, and weapon possession; or change attitudes, beliefs, and perceptions about violence; or both. Direct approaches that are targeted at adolescents are by their nature more policy focused and as such merit a separate review of their effectiveness elsewhere.
The WHO states that social development programmes aim to develop "social skills and competencies including: anger management, problem-solving, conflict resolution, assertiveness, active listening, knowledge about healthy relationships and empathy" (Sethi 2010, p. 53). Social development programmes take the form of classes and will be included in this review if they aim to develop one of the aforementioned skills in young people aged to 12 to18 years and take place in a community setting (e.g. community centres, church halls, and youth centres). We will take community-level interventions to be those that are implemented in community settings rather than those targeting aspects of community life or dynamics, or both.These classes may or may not be combined with diversionary activities or mentoring programmes, which also aim to enhance a young person's social development. Programmes that aim to reduce violence among young people already known to be engaging in violent behaviour are considered a form of secondary (i.e. addressing the presence of risk factors for violence) or tertiary (i.e. preventing the re-occurence of violence) prevention and are significantly different to warrant a separate review.
How the intervention might work
Social development interventions (as detailed in Description of the intervention) are thought to work by reducing the influence of risk factors (as detailed in Description of the condition) and developing protective factors (Sethi 2010).
The concept of protective factors comes from a large body of empirical research in developmental psychopathology on resilience, which suggests that some children and adolescents have the capacity for successful adaptation (i.e. maintaining internal states of well-being and effective functioning) and for not engaging in problem behaviour (e.g. alcohol and drug abuse, antisocial behaviour) despite challenging or threatening circumstances that are considered risk factors for such behaviour (e.g. living in poverty; see Garmezy 1984; Masten 1990; Werner 1993; Luthar 2000). Further research evaluating the involvement of adolescents in problem behaviour has identified protective factors as being one explanation for this ability to avoid problem behaviours and maintain psychosocial well-being in the presence of risk factors (Hawkins 1992; Newcomb 1992; Jessor 1995).
The majority of research on protective factors has been undertaken in relation to antisocial behaviour in general and not specifically to violence; however, it is believed that developing protective factors (particularly individual attributes) can decrease a young person's risk of involvement in violent behaviour by minimising or buffering the effects of risk factors (Office of the Surgeon General (US) 2001; Farrington 2007). The Surgeon General's Report on Youth Violence proposed a number of potential protective factors, including intolerant attitudes toward deviance and violent behaviour (reported as potentially having the strongest effect), high IQ, positive social orientation, perceived sanctions for transgressions, supportive relationships with parents or other adults, parental monitoring, commitment to school, recognition for involvement in conventional activities, and having friends who engage in conventional activities (Office of the Surgeon General (US) 2001).
A substantial body of research in this area led to the development of the social developmental model, which is a general theory of behaviour, grounded in control theory, social learning theory, and differential association theory. It hypothesises that antisocial or pro-social behaviour can be predicted by the presence of risk and protective factors (Catalano 1996a; Catalano 1996b). The theory predicts that interventions that enhance protective factors (e.g. bonding with families) can reduce the effects of risk factors and set children and adolescents on a different developmental trajectory with positive outcomes (Hawkins 1999). This theory consequently underpins indirect violence prevention programmes for 12 to 18 year olds, which targets knowledge, skills, and attitudes to reduce involvement in violence (Farrell 2001), and can be delivered as social development programmes.
Social development programmes are believed to enhance protective factors for violence by developing pro-social skills (see Figure 1) which can be defined as competence in peer interactions and friendships, and interpersonal conflict resolution skills (Grossman 1997). Enhancing skills and competencies (as detailed in Description of the intervention) can enable young people to develop and maintain healthy relationships, and provide them with alternative skills to deal with conflict and solve problems without violence (WHO 2009). A social skills development approach has demonstrated success in school-based violence prevention interventions, with a systematic review reporting that such programmes were associated with 19.1% relative change (i.e. reduction in violent outcome) in the intervention group compared to the control group (Hahn 2007). However, no systematic review has been conducted to evaluate the effectiveness of such programmes in a community setting. Social development programmes may have a mentoring element, which pairs young people with a volunteer who will provide support, understanding, experience, and advice (Roberts 2004). It is believed such relationships may help develop interpersonal skills, and help young people cope with and avoid a high-risk lifestyle (Mihalic 2004). Social development programmes may also incorporate diversionary activities that aim to provide young people with an alternative to antisocial behaviour by reducing boredom and unsupervised leisure time, while also improving social skills and enhancing community involvement (Morris 2003).
Why it is important to do this review
Violence is a leading cause of death and disability in young people aged 15 to 29 years worldwide (Mercy 2002), and is associated with health-risk behaviours (e.g. alcohol and drug abuse) and the development of chronic diseases (Felitti 1998). Despite, the belief that "violence is preventable, not inevitable" as stated in the World Report on Violence and Health (Dahlberg 2002, p.3), the actual evidence base for violence prevention interventions is in need of further development (Rutherford 2007).
To date, systematic reviews examining the effectiveness of universal youth violence prevention interventions have focused on school-based programmes (Cooper 2000; Mytton 2002; Wilson 2003; Hahn 2007), dating violence prevention (Fellmeth 2011), and youth gang involvement prevention (Fisher 2008a; Fisher 2008b). These issues are important to understanding what works in the prevention of youth violence; however, they are either specific to a type of violence (dating and gang) or location (school) or have been limited to interventions conducted in the US (Limbos 2007). Indeed, the majority of social development programmes that aim to reduce violence in children and adolescents have been developed and evaluated in high-income countries, in particular the US (WHO 2009), and may not, therefore, be applicable to other nations.
While there is some evidence for the effectiveness for community-based social development programmes in the prevention of youth violence (see Description of the intervention), no systematic review of such interventions has been undertaken. Due to the potential importance of community-based social development interventions, particularly to engage the most at-risk youths, a systematic review of global interventions in this area is necessary to inform violence prevention policy and guide the development of future interventions.